The invention relates generally to guiding catheters and, more particularly, to Doppler assisted guiding catheters useful for locating and cannulating vessels of a patient""s heart.
Catheters are used in a wide variety of medical procedures. In some applications, these devices provide physicians the ability to explore, operate, and insert drugs/medical devices in various reaches of the anatomy without invasive surgery. Oftentimes, the catheters have medical devices mounted on the catheter shaft, such as in an electrophysiological (EP) ablation catheter, wherein an ablation electrode is mounted at a distal tip of the catheter. In another application, guiding catheters are used to create an easily navigable pathway to be used for delivery of various payloads such as drugs, therapeutic/diagnostic devices (e.g., EP mapping and ablation electrodes), and implantable devices (e.g., cardiac pacing/defibrillation leads).
Guiding catheter systems are typically configured with a profile that is optimized for the intended method of access. For example, when trying to access the coronary sinus of a patient""s heart, one method is to enter the venous system through an incision at a large vein such as the subclavian vein near the shoulder. A guiding catheter is inserted through this incision and is displaced in an arced path through the superior vena cava into the right atrium of the heart. From the right atrium, the ostium of the coronary sinus must be located. A catheter with a distal contour including a relatively sharp bend will point the catheter towards the likely location of the coronary sinus once the right atrium is reached. The contours of pre-shaped guiding catheters are often fixed during manufacture.
A pre-shaped guiding catheter is sometimes used to blindly locate the coronary sinus ostium. This endeavor, however, is complicated by the fact that the location of the coronary sinus ostium may vary appreciably from one patient to another, especially among patients with diseased hearts. Further, the size and flexibility of the catheter that provides maneuverability through the convoluted access path becomes a disadvantage when trying to manipulate the distal end of the catheter in the right atrium.
The primary goal of a guiding catheter procedure is to locate and cannulate a vessel of interest safely and in the least amount of time. Finding and cannulating the coronary sinus, for example, can become a time consuming, trial and error procedure even in a healthy patient. Patients exhibiting symptoms of advanced heart disease can have blockages or deformations of heart structure, further complicating the task of locating the ostium.
Some common techniques are used to aid the physician in visualizing the distal end of a guiding catheter during cannulation. These techniques include the procedures of angiography and venography. The procedures involve injecting a radioopaque dye into the bloodstream to X-ray map blood vessels. Typically, the catheter is radioopaque as well in order to be clearly located. Although effective, this method requires exposing the patient to radiation, and therefore exposure times are necessarily limited. Further, injection of the dye can cause local thrombophlebitis, though this is now rare with modern contrast agents.
Another approach used in assisting catheter guidance is endoscopy, a technique using a fiber optic camera to visualize the blood vessel interior. This method can be effective, but is expensive and is not always adaptable to the geometries required of a guiding catheter intended for applications such as right heart access.
There is a need for an improved guiding catheter allowing quicker access to vessels such as the coronary sinus. There is a need for a simplified method of identifying such vessels and assisting a physician in cannulating a target vessel with a guiding catheter. The present invention fulfills these and other needs, and addresses other deficiencies of prior art implementations and techniques.
The invention relates to a guiding catheter which employs Doppler sensing for accessing various anatomical regions, particularly certain regions of the heart. In one embodiment, a guiding catheter used for locating a patient""s circulatory structure includes a flexible shaft. A Doppler sensor is disposed at a distal end of the flexible shaft. The Doppler sensor senses a blood flow turbulence within a patient""s blood vessel accessed by the distal end of the flexible shaft. The sensed blood flow turbulence indicates a direction to move the distal end of the flexible shaft to locate the patient""s circulatory structure. A communication medium is coupled with the Doppler sensor. The communication medium effects transmission of a Doppler sensor reading to a proximal end of the flexible shaft.
According to one configuration, a processing device is coupled to the communication medium. The processing device processes the sensed blood flow velocity to indicate a turbulence level. The sensed blood flow turbulence indicates a transition between a turbulent flow and a laminar flow. This transition indicates the presence of the patient""s circulatory structure. The Doppler sensor can be arranged to sense one or both of an axial and radial turbulence component. A comparison of the radial and axial turbulence components indicates the presence of the patient""s circulatory structure of interest.
In accordance with another embodiment, a method for cannulating a destination blood vessel involves introducing the distal end of a guiding catheter comprising a flexible shaft and a Doppler sensor disposed at a distal end of the flexible shaft into a patient""s access vessel. The guiding catheter is distally advanced through a circulatory pathway. Blood flow turbulence readings are monitored from the Doppler sensor of the guiding catheter to indicate the presence of the destination blood vessel. The distal tip of the guiding catheter is guided based on the blood flow turbulence readings to locate the destination blood vessel.
A payload can be delivered through an open lumen of the guiding catheter after cannulating the destination vessel. The payload can be a cardiac pacing lead or an injection of fluid, for example. The destination blood vessel can include the coronary sinus of the patient""s heart, and the circulatory pathway can include the right atrium of the patient""s heart accessed via the superior vena cava.
The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.